I once lived in an apartment in Colorado with a balcony overlooking a pond. Once a grebe was paddling around in it followed by four chicks. It was a great image for the Colorado Tourism Office. Then mamma grebe swam back and swallowed the fourth chick whole, and the smaller family paddled away.

Brood reduction isn't common in grebes, but I saw it anyway, and thought maybe I didn't get the straight dope from Disney movies growing up.

Perhaps this is somewhat like male lions killing cubs that are not immediately theirs? Do the seals kill their own pups? Difficult to study, I guess.

The ending reminds me of the “Americans are obsessed with protein” article

Ah, nature thats more like it. Less wholesome, more cthullu.